The present invention relates to a method for judging coercive force of a magnetic card. More particularly, the present invention relates to a method for judging coercive force of a magnetic card, which is preferable for a magnetic card reader having a function for automatically judging a level of coercive force of a magnetic card.
It has been conventionally general to use magnetic cards having the same coercive force in a magnetic card reader. That is, the coercive force of the magnetic card to be used is previously specified by a signal from a host device, and the magnetic cards with two or more types of the coercive force are not designed to be processed by the same magnetic card reader.
In recent years, the coercive force of the magnetic card tends to be increased. For example, there is a tendency such that a low coercive force card having the coercive force of 300 Oe is switched to a high coercive force card having the coercive force of 2750 Oe. Thus, there is a possibility that both the low coercive force card and the high coercive force card may be simultaneously used in a transition period. In general, in case of writing data on the magnetic cards having the different types of coercive force, a suitable card output can not be obtained unless an appropriate write electric current according to the coercive force is set. Therefore, in order to set an appropriate write electric current in accordance with the coercive force of the magnetic card irrespective of a command from a host device, the magnetic card reader must be provided with a function for making judgment upon whether the magnetic card is a high coercive force card or a low coercive force card.
It is, therefore, an object of the present invention to provide a method for judging coercive force of a magnetic card, which can judge the coercive force of a magnetic card used based on an inserted card.
To achieve this aim, according to the present invention defined in claim 1, there is provided a method for judging coercive force of a magnetic card for reproducing or recording magnetic information formed on a low coercive force card or a high coercive force card inserted from a card slot by a magnetic head, wherein after erasing data of the inserted card by an electric current capable of erasing data of only a low coercive force card, data of the card is reproduced and the inserted card is determined as a low coercive force card when the data has been destroyed. Therefore, the coercive force of the magnetic card is determined by judging upon whether the data has been destroyed by the electric current capable of erasing data of only the low coercive force card. Further, since the function for judging the coercive force of the card can be provided to the magnetic card reader in this way, it is possible to provide the magnetic card reader which can execute the write processing by using an appropriate write current with respect to each card.
Further, according to the present invention defined in claim 2, there is provided a method for judging coercive force of a magnetic card for detecting whether a card inserted from a card slot is a low coercive force card and reproducing or recording magnetic information formed on the card by a magnetic head, wherein after erasing data of the inserted card by an electric current capable of erasing data of only a low coercive force card, data of the card is reproduced and the inserted card is determined as a low coercive force card when the data has been destroyed. Therefore, judgment is made upon whether the inserted card is the low coercive force card or any card other than the low coercive force card based on whether data has been destroyed by the electric current capable of erasing data of only the low coercive force card.
In these cases, it is desirable that the destruction of the data is judged by the number of times of flux reversal of reproduced data or by no recognition of specific data which should be recorded in a predetermined card as in the method for judging the coercive force of the magnetic card according to the present invention defined in claim 3. In such a case, when the number of times of flux reversal of reproduced data is smaller than the usual number of times of flux reversal according to recording density of a magnetic stripe, or when specific data which should be recorded is not recognized, it is considered that the data has been destroyed, thereby making judgment upon whether the inserted card is a low coercive force card.
That is, when the number of times of flux reversal of reproduced data is smaller than the usual number of times of flux reversal according to recording density of a magnetic stripe, or when specific data which should be recorded is not recognized, it is considered that the data has been destroyed, and hence it is possible to determine that the card is a low coercive force card in these cases.
Furthermore, according to the present invention defined in claim 4, there is provided a method for judging coercive force of a magnetic card for reproducing or recording magnetic information formed on a low coercive force card or a high coercive force card inserted from a card slot by a magnetic head, wherein after rewriting data on the inserted card by an electric current capable of rewriting data of only the low coercive force card, data of the card is reproduced, and the inserted card is determined as the low coercive force card when the data has been destroyed. Therefore, the coercive force of the magnetic card can be judged based on whether the data has been destroyed by rewriting the data by an electric current capable of rewriting data of only the low coercive force card. Further, since a function for judging the coercive force of the data can be provided to the magnetic card reader, it is possible to provide the magnetic card reader which can be subjected to the write processing by a write electric current appropriate for each card.
In this case, it is desirable to judge destruction of the data by the fact that specific data which should be recorded on a predetermined card is not recognized as in the method for judging the coercive force of the magnetic card according to the present invention defined in claim 5. In such a case, it can be considered that the data has been destroyed when the specific data which should be recorded is not recognized, thereby making judgment upon whether the card is the low coercive force card.
That is, since it can be considered that the data has been destroyed if the specific data which should be recorded is not recognized, it is possible to determined the card as the low coercive force card.
Further, according to the present invention defined in claim 6, there is provided a method for judging coercive force of a magnetic card for detecting whether a card inserted from a card slot is a low coercive force card and reproducing or recording magnetic information formed on the card by a magnetic head, wherein after rewriting data of the inserted card by an electric current capable of rewriting data of only the low coercive force card, the data of the card is reproduced, and the inserted card is determined as the low coercive force card if the data has been destroyed. Therefore, judgment is made upon whether the card is the low coercive force card or any card other than the low coercive force card based on destruction of the data after rewriting the data by an electric current capable of rewriting data of only the low coercive force card.
Furthermore, according to the present invention defined in claim 7, there is provided a method for judging coercive force of a magnetic card for detecting whether a card inserted from a card slot is a high coercive force card and reproducing or recording magnetic information formed on the card by a magnetic head, wherein after rewriting data of the inserted card by an electric current capable of rewriting data of only the low coercive force card, the data of the card is reproduced, and the inserted card is determined as the high coercive force card when the data has not been destroyed. Accordingly, since data is not actually rewritten even if there is an attempt to rewrite data by using an electric current capable of rewiring data of only the low coercive force card, judgment is made upon whether the card is the high coercive force card or any card other than the high coercive force card based on the fact that data has been destroyed or not.
In such a case, as similar to the method for judging coercive force of a magnetic card according to the present invention defined in claim 8, it is desirable to judge the state of the data which has not been destroyed based on recognition of specific data which should be recorded on a predetermined card. In this case, it can be considered that the data has been destroyed if the data has been actually rewritten. Meanwhile, it can be considered that the data has not been destroyed if the data has not actually been rewritten. Thus, it is possible to make judgment upon whether the card is the high coercive force card or any card other than the high coercive force card.
In other words, since it can be considered that the data has not been destroyed when specific data which should be recorded is recognized, it is possible to determined that the card is the high coercive force card in this case.
Moreover, according to the present invention defined in claim 9, there is provided a method for judging coercive force of a magnetic card for reproducing or recording magnetic information formed on a low coercive force card or a high coercive force card inserted from a card slot by a magnetic head, wherein after erasing data of the inserted card by an electric current capable of erasing data of the low coercive force card and the high coercive force card, data is written by using an electric current capable of writing data of only the low coercive force card, and the inserted card is determined as the low coercive force card when the data is thereafter reproduced and an appropriate reproduction state is obtained. Therefore, the coercive force of the magnetic card is judged by whether the data written after being erased is appropriately reproduced. In addition, since the magnetic card reader can be provided with the function for judging the coercive force of the card in this manner, it is possible to provide the magnetic card reader which can execute the write processing by using an appropriate write electric current with respect to each card.
In this case, as in the method for judging coercive force of a magnetic card according to the present invention defined in claim 10, it is desirable to judge the appropriate reproduction state of data based on the number of times of flux reversal of the reproduced data or recognition of specific data which should be recorded on a predetermined card. In this case, when the number of times of flux reversal of the reproduced data is smaller than the usual number of times of flux reversal according to the recording density of a magnetic stripe, or when the specific data which should be recorded is not recognized, it can be considered that the reproduction state of the data is inappropriate, thereby making judgment upon whether the card is the low coercive force card.
That is, when the number of times of flux reversal of reproduced data is smaller than the number of times of flux reversal according to the recording density of a magnetic stripe, or when specific data which should be recorded can not be recognized, it can be considered that the reproduction state of data is inappropriate. In such a case the card can be determined as a high coercive force card.
Further, according to the present invention defined in claim 11, there is provided a method for judging coercive force of a magnetic card for detecting whether a card inserted from a card slot is a high coercive force card and reproducing or recording magnetic information formed on the card by a magnetic head, wherein after erasing data of the inserted card by an electric current capable of erasing data of a low coercive force card and a high coercive force card, data is written by an electric current capable of writing data of only the low coercive force card, and the inserted card is determined as a high coercive force card if appropriate reproduction is impossible when the data is reproduced. Therefore, the magnetic card is judged as the high coercive force card or any card other than the high coercive force card depending on whether the data written after the erasure can be appropriately reproduced.
In this case, as in the method for judging coercive force of a magnetic card according to claim 12, it is desirable to determine that appropriate reproduction is impossible when the number of times of flux reversal of a reproduction output is smaller than the usual number of times of flux reversal according to the recording density of a magnetic stripe. In this case, it can be considered that reproduction of data is inappropriate, i.e., reproduction is impossible when the number of times of flux reversal of the reproduced data is smaller than the usual number of times of flux reversal according to the recording density of the magnetic stripe. It is, therefore, possible to determine the card is a high coercive force card or any card other than the high coercive force card.
That is, if the number of times of flux reversal of the reproduction output is smaller than the usual number of times of flux reversal according to the recording density of the magnetic stripe, it can be considered that the reproduction state of the data is inappropriate, i.e., the appropriate reproduction is impossible. In such a case, it is possible to determine the card as a high coercive force card.
Further, according to the present invention defined in claim 13, there is provided a method for judging coercive force of a magnetic card for detecting whether a card inserted from a card slot is a low coercive force card and reproducing or recording magnetic information formed on the card by a magnetic head, wherein after erasing data of the inserted card by using an electric current capable of erasing data of a low coercive force card or a high coercive force card, data is written by using an electric current capable of writing data of only a low coercive force card, and the inserted card is then determined as a low coercive force card when the reproduction state is appropriate at the time of reproducing the data. Therefore, judgment is made upon whether the magnetic card is a low coercive force card or any card other than the low coercive force card based on whether the data written after erasure can be appropriately reproduced.
Further, as in the method for judging coercive force of a magnetic card according to claim 11, it is desirable that the reproduction state of the data is determined as the appropriate reproduction state when specific data which should be recorded on a predetermined card is recognized. In this case, it can be considered that the reproduction state of the data is appropriate when specific data which should be recorded is recognized, thereby determining the card as a low coercive force card or any card other than the low coercive force card.
That is, if the specific data is recognized during reproduction output, it can be considered that the reproduction state of the data is appropriate, i.e., the appropriate reproduction state is obtained, and hence the card can be determined as a low coercive force card.